As a Christian pacifist, I'm extremely wary of militaristic language, in either common speech ("bullet points" or "I got bombed last night") or allegedly spiritual discourse ("Onward Christian soldiers, marching off to war..."). So I was initially put off by the title _Unseen Warfare_. But as soon as I began reading the book, it becane clear that the type of warfare discussed was quite different from what we usually take the word to mean.
Scupoli (along with Nicodemus & Theophan, his Orthodox editors) argues that Christian perfection lies in aligning one's will with God's, but that this alignment is extremely difficult because an entire army of contrary "wills" resides in us, continuously dragging us away from God. In order to counter these "wills," the Christian must arm herself with "invisible weapons." The "most trustworthy and unconquerable" of them are: (1) never rely on yourself in anything; (2) always bear in your heart a perfect and all-daring trust in God alone; (3) strive without ceasing; and (4) remain constantly in prayer.
It's clear that these weapons, rather than seeking to overpower by sheer brute strength, take seriously the strength-through- powerlessness that St. Paul writes about. Unseen warfare is fought not by pitting one's will against a foe, but by surrendering oneself to God; not by trusting in one's own resources, but by acknowledging dependence; not by risking everything on one flashy, dramatic battle, but by persevering, little by little, day by day; and not by drawing up battle plans so much as by ceaseless praying. The language may be militaristic, but the purport of the language actually subverts the violence and self-assertion associated with war. It speaks of self-sacrifice, love, devotion, discipline.
_Unseen Warfare_ is a sobering read, because it convicts the reader (or at least it convicted THIS reader) of falling woefully short in the quest for Christian perfection. But it's also an inspiring and ennobling read, because it encourages the reader to greater resolve. Highly recommended.